From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@linaro.org>
Subject: Re: [PATCH RFC 32/35] arm : acpi map xen environment
	table to dom0
Date: Fri, 06 Feb 2015 08:57:21 +0800
Message-ID: <54D41171.10901@linaro.org>
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Parth Dixit <parth.dixit@linaro.org>
Cc: ian.campbell@citrix.com, tim@xen.org, xen-devel@lists.xen.org, stefano.stabellini@citrix.com, jbeulich@suse.com, christoffer.dall@linaro.org
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Hi Stefano,

On 06/02/2015 01:36, Stefano Stabellini wrote:
> On Wed, 4 Feb 2015, parth.dixit@linaro.org wrote:
>> From: Parth Dixit <parth.dixit@linaro.org>
>>
>> xen environment table contains the grant table address,size and event
>> channel interrupt information required by dom0.
>>
>> Signed-off-by: Parth Dixit <parth.dixit@linaro.org>
>> ---
>>   xen/arch/arm/arm64/acpi/arm-core.c | 52 +++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 51 insertions(+), 1 deletion(-)
>>
>> diff --git a/xen/arch/arm/arm64/acpi/arm-core.c b/xen/arch/arm/arm64/acpi/arm-core.c
>> index 9fd02f9..9e9285c 100644
>> --- a/xen/arch/arm/arm64/acpi/arm-core.c
>> +++ b/xen/arch/arm/arm64/acpi/arm-core.c
>> @@ -33,7 +33,6 @@
>>   #include <asm/cputype.h>
>>   #include <asm/acpi.h>
>>   #include <asm/p2m.h>
>> -
>>   /*
>>    * We never plan to use RSDT on arm/arm64 as its deprecated in spec but this
>>    * variable is still required by the ACPI core
>
> Spurious change
>
>
>> @@ -297,6 +296,49 @@ static int map_stao_table(struct domain *d, u64 *mstao)
>>       return 0;
>>   }
>>
>> +static int map_xenv_table(struct domain *d, u64 *mxenv)
>> +{
>> +    u64 addr;
>> +    u64 size;
>> +    int res;
>> +    u8 checksum;
>> +    struct acpi_table_xenv *xenv=NULL;
>> +
>> +    xenv = ACPI_ALLOCATE_ZEROED( sizeof(struct acpi_table_xenv) );
>> +    if( xenv == NULL )
>> +            return -ENOMEM;
>> +
>> +    ACPI_MEMCPY(xenv->header.signature, ACPI_SIG_XENV, 4);
>> +    xenv->header.length = sizeof(struct acpi_table_header)+12;
>> +    xenv->header.checksum = 0;
>> +    ACPI_MEMCPY(xenv->header.oem_id, "XenVMM", 6);
>> +    ACPI_MEMCPY(xenv->header.oem_table_id, "RTSMVEV8", 8);
>> +    xenv->header.revision = 1;
>> +    ACPI_MEMCPY(xenv->header.asl_compiler_id, "INTL", 4);
>> +    xenv->header.asl_compiler_revision = 0x20140828;
>> +    xenv->gnt_start = 0x00000010000000;
>> +    xenv->gnt_size = 0x20000;
>> +    xenv->evt_intr = 31;
>> +    xenv->evt_intr_flag =3;
>> +    size = sizeof(struct acpi_table_xenv);
>
> As per all the other checksum calculation, I wonder whether we need a
> memory barrier here.

I don't see why the memory barrier is necessary, the checksum and the 
modification of the table is done on the same processor.

But cleaning/invalidate the cache after the checksum may be required.

Regards,

-- 
Julien Grall